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How to fly DME arcs?

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fussle

Oh John...
Joined
Dec 12, 2003
Posts
69
What is the best procedure to fly DME arcs when being vectored? How far do you know you need to turn? I have always hear turn 90 degree, but what if the controller vectors you higher along the arc and at an angle?
 
turn 80 degrees (in the direction you plan to arc) from the radial you are on when you intercept the arc. 90 degrees is too much, you end up flying away from the arc.
 
Center up the needle then turn to the heading that is 90 degrees off your CDI. Distance will depend on the amount of degrees you need to turn also on your airspeed.
 
Do you have an RMI, if so then turn until the RMI is pointing straight out either your left or right wing at the station (depending on the direction of turn) and turn as necessary to hold it there as you progress around the arc. This is the easiest way if you have the equipment.
 
what Fox6 said plus

bring up your wind vector on your EFIS to help out with correction angle

I use that on the rare NDB approach and I nail it every time
 
Center the CDI with a FROM indication, when yo are about a mile from the arc, turn 90 degrees from the top of the OBS (or 80, 90 is just an easier way to figure out what heading you shold be at in still air).

To decide if you are going to turn left or right, just look atthe arc, and if when established the arcgoes to the right, then you want to turn to the heading that is to the right of the top of the OBS, if left, then go to the heading 90 degrees to the left of the top of the OBS.

Remember that this only works if you have a FROM indication, if you have a TO indication you still can do it but would be the opposite.

As you keep flying the arc, if youkeep centering the CDI, you will still see the heading you have to be at either at the right of the oBS or left.

Next thing to do is to figure what the wind is doing to you, and you can start by adding 10 degrees into the wind and see how that works.

Hope that helps.
 
Everyone here is correct, and I know I'm repeating what everyone else said, but just remember this...When you get about 1 mile from the arc, turn to a heading 90 degrees off of the COURSE(use the CDI) you're on from the VOR, NOT 90 degrees off of your current HEADING. 2 very different things. It's a very common mistake I've seen many a student make.

This would not be a big deal if you were always flying straight to the VOR, but if you get a vector to some other place on the arc and you're not flying directly towards the VOR, it gets confusing which way to turn unless you always remember...90 degrees off of course.
Hope this helps.
 
hope the arc is published and that its in the FMS Database.....arm the approach with the Arc transition and let it fly it for you.
 
90 if intercepting from the inside of the arc.

80 degrees if intercepting from the outside (the usual way in the real world).


Draw it out and do the math. In stil air, 90 put you outside of the arc immediately, unless you turned late (another option).
 

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